Load carriers in particular of the kind fixed to the wheel of a vehicle have become increasingly popular. Known load carriers typically comprise a designated function such as carrying bikes. In other words, the load carriers are typically designed for a specific purpose. On the other hand, load carrier systems are known in which a base part is mountable on the rear of a vehicle and different types of carrier elements designed for a specific purpose are mountable on that base part. Such a configuration allows to change the purpose of the overall load carrier system by interchanging carrier elements and mounting them on the base part. For instance, it is possible in such systems to mount a bike carrier element on the base part and in case additional storage space is necessary, to mount a corresponding carrier box on the base part. As the latter systems are typically more costly, there exists the need to provide an interchangeability of functions of load carriers fixed to the rear of a vehicle. In this connection, systems are available which allow to place and mount a bag or load receptacle on an existing load carrier. For example, there are systems available in which the load carrier is a bike carrier and a load receptacle is mounted on the bike carrier.